The present invention relates to a method of rolling by flat cutters, and more particularly to a rolling method which comprises rolling a pipe to form splines, serrations or the like on its periphery by the flat cutters.
As a conventional rolling method, there is a rolling method as shown in FIGS. 1 to 3, for example.
As shown in FIG. 1, a workpiece 1 consisting of a solid rod is rotatably supported at the center of both ends by a pair of conical centers 2. Subsequently, the workpiece 1 is rolled on its periphery by means of a pair of longitudinally extending flat cutters 3 shown in FIG. 2. Each of the flat cutters 3 has a plurality of corrugated working blades 4 formed to extend laterally on an upper surface of the body, the working blades 4 consisting of rough blades 5, medium blades 6 and finishing blades 7, which gradually increase in height from an initial portion to a terminal in a longitudinal direction.
At the time of working, a pair of flat cutters 3, 3 are disposed with the working blades 4 thereof facing each other, so that a workpiece 1 is charged between them with its axis parallel to the blades 4. Then, both of the flat cutters 3 are moved rectilinearly in opposite directions towards each other so that the peripheral portion of the workpiece 1 can be rolled. Subsequently, as shown in FIG. 3, the rolled workpiece 1 is held by a chuck 8 and cored by a drill 9 to obtain a rolled pipe product.
In such a conventional rolling method, since a workpiece consisting of a solid rod is rolled on the periphery and subsequently the workpiece is cored by a drill, the working operation takes much time and the working procedures are complicated. For solving this problem, if a pipe is used as a workpiece, there would be a problem in that rolling with high accuracy would be difficult because the conventional flat cutter 3 has the working blades 4 formed horizontally throughout a width w (FIG. 2) of the cutter and the working blades 4 simultaneously press the portion of the workpiece to be rolled, resulting in deformation of the workpiece consisting of a pipe in the axial direction. In addition, in the conventional flat cutter 3, since the working blades 4 are formed horizontally throughot the width w, the working blades 4 are worn out evenly in the direction of width of the body. Therefore, it is difficult to extend the life of the cutter by reabrading the worn portion of the working blades.